AMORPHOPHALLUS KHANHHOAENSIS

PROTOLOGUE: Amorphophallus khanhhoaensis , published in Phytotaxa 750 (1): 051–057 (2026).

Amorphophallus khanhhoaensis V.D.Nguyen, Q.D.Dinh & Hett., sp. nov. Type: VIETNAM. Khanh Hoa: Dien Khanh, Dien Xuan, near by Dong Moc lake to north, 12°19'51.73 N, 108°59'46.77" E, July 2024, Dinh Quang Diep s.n (holotype, HN!).

DISTRIBUTION: Vietnam, Khánh Hòa.

DISTRIBUTION NOTE: Vietnam: Khanh Hoa Province, Dien Khanh District (near the Dong Moc lake area)².

SPECIES DESCRIPTION:

Plants herbaceous, tuberous, c. 2.5 m tall. Tuber subglobose or depressed globose, ca. 15–20 cm diam., concave at the apex, surface with few or many short, small, conical, lateral offsets and slightly raised root scars. Leaf solitary; petiole stout, to ca. 1.5 m long, 6–7 cm diam. at the base, c. 4 cm in diam. at the top, uniformly mid to pale brown, smooth; leaf blade highly decompound, c. 1 m across, with 3 large lobes, each lobes devided pinnately 2-3 times to pairs of smaller lobes, small lobes bearing leaflets; main rhachises without wing at basic halves, winged at upper and branched rachises; leaflets sessile, green, glossy on both surfaces, narrowly elliptical or oblong obovate, size 8–25 x 3.5–6 cm, 1 side of base attenuate along the rachis as a wing, apex acute or acuminate, 1–2 cm long; wings 0.3–2 cm wide; venation on the lower surface very prominent, collective vein quite distant from the margin.²

INFLORESCENCE:

Inflorescence solitary; peduncle cylindrical, subterete, slightly narrower to apex, 60 cm long, 1.5 cm diam. at the base, 1.2 cm at the apex, pale brownish-green, smooth, outer cataphyll c. 30 cm long; spathe erect, elongate elliptic, 20–28 cm long; base convolute, cylindric, 8–10 cm long, outside very pale whitish-pink, inside creamy white, upper margin near opening reddish purple, lamina oblong or ovate, 12–15 cm long, 8–10 cm wide, margin irregularly undulate, inside at first pale yellowish-green with a purple base, later carnose red or purple at the middle, outside margin pale carnose red, remainder pale brownish or pale yellowish. Spadix sessile, shorter than spathe, 19.5 cm long; pistillate zone cylindric, c. 3.5 cm long, 2 cm diam., sometime slightly narrowerer at the top, ovaries densely crowded; staminate zone elongate conical, 6.5–8.5 cm long, 1.6–2.2 cm diam. at the base, 1.2–2 cm at the apex; appendix short conical, shorter than staminate zone, sometimes even shorter than half the length of the staminate zone, 2.7–9 cm long, base equal to or wider than apex of the staminate zone, 1.6–2.5 cm diam. at the base, apex rounded or acute, surface creamy white, paved with very small (1–1.5 mm diam.), polygonal, truncate staminodes. Ovary depressed globose, c. 2 mm diam., 1.5 mm high, whitish-green to pale green, unilocular, uni-ovulate; style cylindrical, 1 mm long, off-white; stigma disciform, nearly as wide as the ovary, organge yellow, later brownish-yellow then dark brown; staminate flower consisting of 3–4 stamens, stamens 2 mm long, anthers golden yellow, with a shallow central depression, c. 1 mm wide, dehiscence by wide, apical pores. Fruits not observed.²

ECOLOGY:

Found commonly in disturbed tropical rainforest on a stony mountain, appearing from below boulders in a vegetation with Jasminum subtriplinerve, several Convolvulaceae, Aletris cochinchinensis, and Drynaria bonii including ground dwelling plants, like gingers, Alocasia cf. odora and Pecteilis cambodiana.²

ETYMOLOGY:

Named for Khanh Hoa Province in south-central coastal Vietnam, the only place the species is known; the Latin suffix-ensis marks the place of origin.²

NOTES:

1. Amorphophallus khanhhoaensis is similar to Amorphophallus umbrinus in the appendix surface being paved with small, polygonal staminodes, an unusual character in the genus Amorphophallus. However, Amorphophallus umbrinus is unique by having a very deep maroon spathe with spots (vs. a creamy white spathe with or without purple flushes and with a deep maroon interior spathe base). Between Amorphophallus cicatricifer, Amorphophallus khanhhoaensis shares a similar spathe and spadix morphology but the spadix of Amorphophallus cicatricifer is smooth and the stigmas have a basisconic marginal lobes (vs. entire in Amorphophallus khanhhoaensis). Also, the tuber of Amorphophallus cicatricifer develops several short cylindrical or fusiform offsets, whereas the tuber of Amorphophallus khanhhoaensis does not produce distinct offsets. Amorphophallus ferruginosus shares the same spathe and spadix morphology with Amorphophallus khanhhoaensis but the former has a smooth appendix, hemispheric stigmas (vs. appendix with polygonan staminodes and disciform stigma in Amorphophallus khanhhoaensis) and the tuber develops numerous, small and broadly atached offsets and numerous easily detaching, small fusiform offsets.²

2. Currently, Amorphophallus khanhhoaensis is only known in Dien Khanh district of Khanh Hoa province, with an estimated distribution area of about 10 km2. The habitat of this species is near Dong Moc tourist area, so it is easily affected if the tourist area has an expansion project or tourist traffic. Therefore, based on the criteria of the IUCN Red List, this species can be classified at level VU B2C2aD2.²

REFERENCES:

1. Phytotaxa 750 (1): 051–057 (2026) — protologue.

Additional photos by Quang Diep Dinh